1. Field of the Invention
The invention relates to an arrangement for supporting a tension member, in particular a stay cable or a prestressing member, transversely with respect to the longitudinal extent thereof in a vicinity of the anchorage of a.
2. Description of the Background Art
Tension members of this type are known primarily as stay cables or external prestressing members of bridge structures, where they have a key function in the accommodation and transfer of loads that are present. For this purpose the tension members, composed of steel rods, steel wires, or steel strands, are tensioned between two components of a structure, the ends of each tension member being guided through the components within a channel and anchored at their rear side. The tension members extend freely in the free area between the anchorings.
Due to dynamic loads such as wind loads or traffic loads, for example, as well as temperature-related deformations of the structure, movements of the tension member in the operating state, in particular also in the transverse direction, are unavoidable. While such movements in the free area are acceptable within limits, they adversely affect the fatigue strength of the tension member in the anchoring area. This is counteracted by intercepting the movements in the transverse direction.
To this end, a tension member which extends in the anchoring area within a pretensioning channel which is formed by a cavity pipe is known from DE 295 04 739 U1. For concentrically fixing the tension member in the pretensioning channel, the tension member is enclosed by a ring tensioning element which on the one hand bundles the individual strands of the tension member before they are spread toward the anchoring, and on the other hand with its outer periphery contacts the inner side of the cavity pipe. In this way, movements of the tension member transverse to its longitudinal extent are limited to the area outside the pretensioning channel, thus increasing the fatigue strength of the tension member.
Due to manufacturing- and installation-related tolerances or the slack in stay cables, it is often the case that the actual longitudinal axis of the tension member differs from the target axis. To take these tolerances into account, it is necessary to fix the tension member eccentrically, not concentrically, in the pretensioning channel. This problem is addressed in the invention described in DE 34 34 620 A1, which corresponds to U.S. Pat. No. 4,648,147, in which a sufficiently large annular chamber which expands the pretensioning channel within the structure via a longitudinal section provides space for the eccentric accommodation of the tension member. After the annular chamber is sealed off, it is pressed with a setting or loose, free-flowing material, thus fixing the eccentric position of the tension member within the pretensioning channel. In many cases this approach has proven satisfactory in practice.
A similar procedure is disclosed in DE 295 17 250 U1, according to which an annular closed pad is arranged around the tension member, forming a closed cavity, so that without further sealing operations, pressing may be carried out using a setting material while at the same time fixing the tension member.
To avoid the expenditure of time and effort associated with the pressing process, it is already known from DE 200 14 322 U1 to situate two circular rings, each having an eccentric opening, inside one another in such a way that they may be rotated relative to one another in the shared circumferential joint. The inner circular ring encloses the tension member, while the outer periphery of the outer circular ring is supported on the cavity pipe. The opening in the inner ring may be adapted to the eccentricity of the tension member by mutually rotating the rings.